A method for separating a substrate into multiple single components is described in U.S. Published Patent Appln. No. 2011/0163079 and German Published Patent Appln. No. 10 2008 001 952, in which the crystal structure is modified along a separation line with the aid of a pulsed laser beam in the depth of a monocrystalline substrate, which is also denoted as stealth dicing or Mahoh dicing.
Wet chemical methods for the production of crystallographically determined caverns have already been in production for many years; however, severe limitations exist in this area, which affects the design of the cavern shape. Known crystallographic etching methods may in particular only be used for implementing caverns having precisely predefined geometries (flank angles) and sizes. In part, the cavern sizes limit the component size and thus prevent miniaturization. In the case of silicon methods, the etching of caverns using KOH as an etching medium is well-known. In the case of a (100)-surface orientation, this generally results in a rectangular pyramid or a truncated pyramid in a preselected etching time.
In addition, in the case of all known etching methods, in particular also in the case of DRIE, the diaphragm dimensions of the cavern on the opposite substrate side are strongly correlated with the thickness of the wafer, since the etching mask is lithographically defined on the rear side in the case of a fixed flank etching angle of the cavern.
FIGS. 4a, b are schematic cross-sectional representations for elucidating an exemplary manufacturing method for a micromechanical component and a corresponding micromechanical component for elucidating the present invention.
In FIG. 4a, reference symbol 1a denotes a first wafer having a thickness da, a mask opening MA of an etching mask (not shown) being defined on its rear side R. If a diaphragm M1a having a predetermined thickness d is etched in wafer 1a through mask opening MA on side V, the lateral dimension of diaphragm M1a is indicated as MMa. This dimension results due to etching flank angle α.
If, however, according to FIG. 4b, a thicker wafer 1b having a thickness db having an identical mask opening MA is etched on the rear side in order to form a diaphragm M1b having thickness d, its diaphragm dimension MMb is smaller than diaphragm dimension MMa because etching flank angle α is identical.
A combined etching method from a DRIE etching and a subsequent KOH etching is described in U.S. Pat. No. 7,514,287, which makes it possible to produce caverns having a waist greater than the etching opening.